Novel reactive thermoplastic resin as a matrix for laminates containing phase change microcapsules

Fredi, Giulia; Dorigato, Andrea; Pegoretti, Alessandro

doi:10.1002/pc.25233

Cited by 45 publications

(36 citation statements)

References 64 publications

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“…This can be due to the presence of microcapsules aggregates and agglomerates, as observed in the SEM micrographs. A similar trend is also observed in the composites, and although the decrease in mechanical properties are also due to the decrease in the fiber volume fraction, it can be concluded that the introduction of a PCM is not beneficial for the mechanical properties, as was already observed in our previous studies on PCM-enhanced composites [36,37,38,40,41].…”

Section: Resultssupporting

confidence: 85%

“…Little has been done so far to develop and characterize such structural TES composites. Recently, our group prepared multifunctional epoxy/carbon laminates comprising carbon nanotubes-stabilized paraffin (CNTs) [36,37], polyamide/glass laminates with a microencapsulated and a shape-stabilized PCM [38,39], PCM-enhanced laminates starting from a novel reactive thermoplastic resin [40], and two types of semi-structural short carbon fibers composites including paraffin microcapsules, based on a thermoplastic (polyamide 12) [41] or a thermosetting (epoxy) [42] matrix, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

et al. 2019

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Organic phase change materials (PCMs) represent an effective solution to manage intermittent energy sources as the solar thermal energy. This work aims at encapsulating docosane in organosilica shells and at dispersing the produced capsules in epoxy/carbon laminates to manufacture multifunctional structural composites for thermal energy storage (TES). Microcapsules of different sizes were prepared by hydrolysis-condensation of methyltriethoxysilane (MTES) in an oil-in-water emulsion. X-ray diffraction (XRD) highlighted the difference in the crystalline structure of pristine and microencapsulated docosane, and 13C solid-state nuclear magnetic resonance (NMR) evidenced the influence of microcapsules size on the shifts of the representative docosane signals, as a consequence of confinement effects, i.e., reduced chain mobility and interaction with the inner shell walls. A phase change enthalpy up to 143 J/g was determined via differential scanning calorimetry (DSC) on microcapsules, and tests at low scanning speed emphasized the differences in the crystallization behavior and allowed the calculation of the phase change activation energy of docosane, which increased upon encapsulation. Then, the possibility of embedding the microcapsules in an epoxy resin and in an epoxy/carbon laminate to produce a structural TES composite was investigated. The presence of microcapsules agglomerates and the poor capsule-epoxy adhesion, both evidenced by scanning electron microscopy (SEM), led to a decrease in the mechanical properties, as confirmed by three-point bending tests. Dynamic mechanical analysis (DMA) highlighted that the storage modulus decreased by 15% after docosane melting and that the glass transition temperature of the epoxy resin was not influenced by the PCM. The heat storage/release properties of the obtained laminates were proved through DSC and thermal camera imaging tests.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

et al. 2019

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“…Both the phase change peaks are composed of at least two component peaks, which are more appreciable in the cooling scan and would be more resolvable by decreasing the heating/cooling rate of the test. As already observed in previous studies investigating a similar PCM, 44 , 45 , 47 , 81 the presence of multiple peaks stems from a sequence of transitions on heating and cooling. The first smaller peak encountered on heating is probably associated with the solid–solid transition from the solid crystalline phase to the so-called “rotator phase,” while the second peak could be ascribed to the solid–liquid transition; analogous transitions are observable on cooling.…”

Section: Resultssupporting

confidence: 79%

Bioinspired Polydopamine Coating as an Adhesion Enhancer Between Paraffin Microcapsules and an Epoxy Matrix

et al. 2020

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Microencapsulated phase change materials (PCMs) are attracting increasing attention as functional fillers in polymer matrices, to produce smart thermoregulating composites for applications in thermal energy storage (TES) and thermal management. In a polymer composite, the filler–matrix interfacial adhesion plays a fundamental role in the thermomechanical properties. Hence, this work aims to modify the surface of commercial PCM microcapsules through the formation of a layer of polydopamine (PDA), a bioinspired polymer that is emerging as a powerful tool to functionalize chemically inert surfaces due to its versatility and great adhesive potential in many different materials. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) evidenced that after PDA coating, the surface roughness increased from 9 to 86 nm, which is beneficial, as it allows a further increase in the interfacial interaction by mechanical interlocking. Spectroscopic techniques allowed investigating the surface chemistry and identifying reactive functional groups of the PDA layer and highlighted that, unlike the uncoated microcapsules, the PDA layer is able to react with oxirane groups, thereby forming a covalent bond with the epoxy matrix. Hot-stage optical microscopy and differential scanning calorimetry (DSC) highlighted that the PDA modification does not hinder the melting/crystallization process of the paraffinic core. Finally, SEM micrographs of the cryofracture surface of epoxy composites containing neat or PDA-modified microcapsules clearly evidenced improved adhesion between the capsule shell and the epoxy matrix. These results showed that PDA is a suitable coating material with considerable potential for increasing the interfacial adhesion between an epoxy matrix and polymer microcapsules with low surface reactivity. This is remarkably important not only for this specific application but also for other classes of composite materials. Future studies will investigate how the deposition parameters affect the morphology, roughness, and thickness of the PDA layer and how the layer properties influence the capsule–matrix adhesion.

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“…However, limited research has been carried out so far to produce such structural TES composites. Some examples are reported in the literature of continuous or discontinuous fiber composites with thermosetting [20][21][22][23][24], thermoplastic [25][26][27][28], or reactive thermoplastic [29,30] matrices. However, the research on continuous-fiber composites with a traditional thermoplastic matrix and TES capability is limited to a single work [25], in which the compaction is performed via film stacking.…”

Section: Introductionmentioning

confidence: 99%

Melt-spun polypropylene filaments containing paraffin microcapsules for multifunctional hybrid yarns and smart thermoregulating thermoplastic composites

Fredi¹,

Bruenig²,

Vogel³

et al. 2019

Express Polym. Lett.

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The present work focuses on the development of polypropylene (PP) filaments containing paraffin microcapsules (MC), aimed at being incorporated in hybrid yarns to produce multifunctional thermoplastic laminates for thermal energy storage (TES). Benchmark experiments carried out on a small-scale melt compounder and piston-type melt spinning device resulted in the successful production of single filaments containing up to 30 wt% of MC, with diameters of 70-140 µm depending on the collection speed and a surface roughness that increases with the MC content. An increase in the MC fraction also determines a rise in the complex viscosity, but this effect is less evident at higher shear rates and likely almost negligible at the deformation rates typical of the spinning process. Although the MC have a considerable thermal stability, the compounded mixtures reported a sensible mass loss in isothermal thermogravimetric analysis (TGA) tests, which is linked to a not negligible MC damage during the compounding. Nevertheless, differential scanning calorimetry (DSC) on the spun filaments evidenced an increase in the phase change enthalpy with the MC content up to approx. 48 J/g, which is remarkably higher than that of similar systems reported in the literature. The elastic modulus and the properties at break decrease with an increase in the MC content, but the fiber strength is acceptable to produce a hybrid yarn and a thermoplastic laminate up to a MC fraction of 20 wt%.

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Novel reactive thermoplastic resin as a matrix for laminates containing phase change microcapsules

Cited by 45 publications

References 64 publications

Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

Bioinspired Polydopamine Coating as an Adhesion Enhancer Between Paraffin Microcapsules and an Epoxy Matrix

Melt-spun polypropylene filaments containing paraffin microcapsules for multifunctional hybrid yarns and smart thermoregulating thermoplastic composites

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